Treatment for animal fiber



- Patented Nev. s, 1940 UNITED STATES PATENT" oFFrcs 2,220,805 I V mmmnrron ANIMAL FIBER Williain' Beach Pratt, .Boston, Mass; Annette HarrisPratt, ,administratrix of said William Beach Pratt, deceased; assignorto Aldox Corporation, Dover, Del, a corporation of Delaware No Drawing.Application July 18,1938, Serial No. 219,823

I 3 Claims. (Ol.-8128) The attachment of the aldehyde radical to thenitrogenous fiber must be carried out in the abence of substances havinga "greater aiiinity for the aldehyde present than the aflinity for thenitrogenous fiber thereof, and is preferably effected in' an aqueousboth free from. substances reacting with aldehyde to form condensationproducts. The subsequent oxidation of the alde-.

hyde radical should also be carried out -in the absence of anysubstantial alkalizing influence.

The fibers are preferably treated in accordance 20. withmyinventionbefore being subjected to ordinary cleansing treatments whichso deteriorate or break down the fibers that their natural characteristics cannot be restored My treatment is applicable to the fibersbefore or after removal from the skins or-in the form of fibers, per se,

-' filaments, yarns or-fabrics.

By my method of treatment, not only is a chemical compound formedbetween the aldehyde and fiber molecules, but the greasy, gummy, waxy;

Q gents.

The lowering of th melti g points of the .grea'ses, waxes, etc., isaccompanied by an increase in the resistivity of the. fiber itself .tothei action of heat, hence the treatment may be car- 40 ried out at; atemperature such that the oils, greases and waxes are rapidlyemulsifiedwithout inluryj to the fiber itself.

The removal of such substances and the subsequent removal of thealdehyde radical gives thefibers a lofty hand and permanent set, makespossible the bleaching of such fibers without dev v solutions are-used,the solubility or dilution is teriorating effects, renders the fibersmore" resistant to the physical effects resultlngrfrom- .washinguntreated fibers in "alkaline solutions, makesthe fibers morehygroscopic,-and improves dye absorption and the tinctorial eii'ectofdyes vmay .be used to'reduce the pH of the bath to cation with waterof the softened, greasy, gummy and like constituents, it should not besuifioiently high to impair the natural elasticity of the fiber or tocause wasteful loss of aldehyde from aqueous solution. The loss ofaldehyde from aqueous solution may be retarded by forming in the bath aloose bedof fibers of substantial thickness.

The attachment of the aldehyde to the molecules of the fiber appears totake place most read= 11y when the bath is substantial y neutral, or hasI101 a. pH of say '7 to 9 and fre e'fromany substance reactive withaldehyde to form a condensation product. Thefiber may have the aldehyde'combined therewith by immersion in a bath, of such pH, containinginitially only trioxymethylene. ll After suflicient aldehyde has beenreleased from the trioxymethylene and attached to the fiber, suitabledetergents, such as neutral soap and borax, may be addedhto the bath tofacilitate ;emulsification and removal of the grease and 0 waxes. A goodattachment of the aldehyde to they fiber, and a somewhat more rapidprocessing is, however, secured when the detergents are added to thebath at the beginning of the aldehyde treatment, since the aldehyde andborax both 2 tend to reduce. the'pH which would result, from the soapalone. If a soap producing a pH of, say, 10.2 is used, sufiicient boraxand'aldehyde around 8. e I 7 My tendency toward decomposition of thesoap is avoided by the maintenance of a temperature below itsdecomposition point and counteracted by'the inclusionIof the borax inthe bath. The action of borax in keepingthe solution at a pH value aslow as possible" without injuring'the properties of the detergent, is ofdistinct advantage in the treatment of animal fiber.

. I'may provide the bath for giving the aldehyde treatment by dilutingwith water-standard com- (0* mercial aqueous solution of formaldehyde ofsay 3.7-to 40 concentration, or I may employ reversible polymerizationproducts of formaldehyde free from extraneous substances. Such productsas trioxymethylene or para-formaldehyde may 45 be employed. Wherecommercial formaldehyde uniformly distributedthrough such solution] re-I gardless of the water temperature, but when 'para-formaldelwdeorutrioxymethylene is em- 50 ployed thetemperature must be raised to atleast. F. to insure complete solubility throughout the aqueous solutionof formaldehyde produced by the splitting up of these polymerizationproducts. But even whenia dilute commercial som 55 tion of formaldehydeis employed, the bath should be maintained at a temperature of at least120 F. in order that the free formaldehyde gas present in the solutionmay adequately act on the greases and gums and combine with the keratinor fibroin on the fiber.

The neutral soap, borax and aldehyde, in the form of trioxymethylene,may be well mixed together in dry form and then dissolved in the waterto form a bath substantially free from substances with which aldehydetends to form condensation products or for which it has a greaterafiinity than it has for the animal fiber. The bath should have atemperature which eifects the liberation of the aldehyde and thechemical combination thereof with the molecular structure of the animalfiber and increase the solubility and factors of emulsification of thegreasy and gummy constituents of the fiber. As the aldehyde lowers themelting points of the greasy and gummy constituents and increases theresistance of the fiber to the action of heat, the treatment can bereadily carried on at a temperature of say 140 F. which is above thepoint to which the aldehyde lowers the melting point of the gummy andgreasy constituents and well below a point injurious to the aidehydetreated fibers.

The aldehyde so combines with the molecules of the fiber as to resistremoval by repeated washings, which washings effect the substantiallycomplete removal of the foreign matter such as grease, lanolin, seresin,and other oily and gummy substances. v

After the washing of the fibers, the aldehyde radical or constituent ofthe keratinous or fibroin molecules is removed by the oxidation thereofinto an acid in the presence of water, which takes the place of thealdehyde radical and hydrates '40: the fibers.

The removal of the aldehyde radical should preferably be eifected bymeans of an oxidizing agent capable of the use in neutral or slightlyacid solutions as it is desirable that the oxida- 5' tion be carried onunder conditions free from alkalizing influences.

I have successfully employed a solution containing. say, 0.25% ofpotassium permanganate (based on the weight of the fiber) and a small mamount of sulphuric acid or magnesium sulphate to act as a buffer inneutralizing any caus tic soda that might be freed through reaction.Other suitable oxidizers for removing the aldehyde after it has beenfirmly attached to the Q fiber molecules and effecting substitution ofwa- The following is a specific example, but by way of illustrationonly, of the carrying out of my invention for the treatment of wool.

A mixtureof say 40.pounds of trioxymethylene,

20 pounds of borax, and 100 pounds of neutral.

soap of low'titer, is dissolved in water sufiicient in amount for thewetting and immersion of say ten thousand pounds of wool. The treatmentmay be carried on in thestandard equipment commonly used for wqolscouring, but the treating tanks should preferably be made of 75 woodand be substantially free from any exposed iron. The treatment may becarried on either in batch or continuously, depending upon the characterof the equipment employed.

The wool is subjected to the action of the solution at a temperaturebetween 120 F. and 140.

F. and preferably in the neighborhood of 130 F. for approximatelyfifteen minutes. At the end of this time the wool is passed through awashing tank where the impurities, soap and any uncombined aldehyde arethoroughly removed from the fiber. The presence of the combined aldehydein the fiber may be tested by treatment of a washed sample with Fehlingssolution. When the aldehyde bath is initially free of detergents, asomewhat longer combining time is generally desirable than wheredetergents are initially present.

The thoroughl cleaned wool is then passed through an aqu ous solutioncontaining say 0.25% of potassi permanganate or sodium permanganate,base on the weight of the wool, and at a tem ature preferably between104 .F. and 120 F. The aldehyde treated fiber acts promptly to reducethe permanganate solution to a clear aqueous solution with thepermanganate salts of decomposition precipitatedin or upon the animalfiber. This precipitation will ordinarily take place in about .tenminutes. When the precipitation is complete, the fibers are passeddirectly into a solution of sodium bisulphite and/or sulphurous acid toremove the decomposition products'from the reduction of permanganate.The wool is then rinsed'inrunning water to wash out the soluble products.so formed; In regular commercial practice, and where it is notnecessary to secure'the highest degree of whiteness, a regular hydrogenperoxide bleach may be employed, or any standard method for bleachingthe wool as is practiced after the usual scouring operation.

The oxidizing treatment may be so limited as to merely free the animalfiber from the aldehyde radical to hydrate'the fiber and permitsubsequent bleaching, or the oxidation may be carried on until the fiberis partially bleached or bleached to a pure white.

I have heretofore pointed out in my co-pending application for Patent2,126,809, whereof the present application is a continuation in part,that nitrogenous fibers having a sulphur containing radical may beadvantageously treated with aldehyde to improve the texture andloftiness of the fibers and with oxidizing agents to prevent theformation of condensation products from. the aldehydic constituent andefiect bleaching of the fiber. of certain fibers are best effected aftersubjecting the fibers to an ammoniacal treatment which attacks thesulphur constituent of the sulphur radical of the fiber, to the ultimateremoval or rearrangement of the sulphur radical. Such am- Such aldehydicand oxidizing treatments moniacal treatment renders the fiber much morereadily susceptible to the action of the aldehydic and oxidizing agents.By such ammoniacal, al-

dehyde, and oxidizing treatments, naturally black yarns composed of orcontaining them, they may -be immersed in and drawn through an aqueoussolution containing approximately 6% of 'ammonia, approximately 1% .ofaldehyde; 1% of neutral soap, and 1% of sodium perborate or othersuitable oxidizing agents based on the treatment without danger offorming condensation products.

After immersion for approximately two hours at a temperature of from 130to 140, the fibers are rendered lofty, white and free from grease anddirt. Should the fabrics be darkly pigmented,

naturally, a larger percentage of oxidizing agent may be used or thefibers may be given repeated treatments until a pure white is obtained.

For degumming and bleaching silk the same treatment may be usedrbut theammonia should be dispensed with.

Howsoever the practice of my invention is carried on, the baths employedshouldcontain no reagents free to combine with aldehyde to formcondensation products or deleteriously effect the nitrogenous fibers,as, for instance, soda ash, caustic soda, trisodium phosphate or sodiumbisulphate. 'The use of soaps that tend to break down readily andrelease alkali at the treatment temperatures should be avoided. Thepresence in a bath containing aldehyde of reagents free to combinetherewith to form insoluble condensation products not only retards orprevents the liberation of free aldehyde gas and the combining thereofwith the molecules of the animal fiber, but may also stain the goods andeven effect removal of some aldehyde radicals which have been attachedto the fiber molecule. The formation of objectionable condensationproducts from the reaction of the aldehyde with such reagents willfrequently take place at lower temperatures than the temperature atwhich aldehyde satisfactorily combines with molecules of animal fiber.Hence while such condensation products of aldehyde and The reaction ofthe aldehyde on the greases and gums inherent in natural animal fibersappears to be both chemical and physical. Their melting points arelowered and they appear to change in surface tension to increase waterab- 5 sorption. They are rendered by my treatment readily removable fromthe animal fiber by washing, particularly when proper detergents oremulsifying agents are employed in a subsequent washingoperation.

Having described my invention, I claim:

1. In the treatment of animal fibers having a greasy or gummyconstituent, the steps which include lowering the melting point of suchconstituent by treatment with an aldehyde in the presenceof a detergentof the group consisting of a neutral soap and borax at a temperaturebelow the decomposition point of the detergent and above the point towhichthe aldehyde lowers the melting point of the constituent.

2. In the treatment of animal fibers having a greasy or gummyconstituent, the steps which include treating the fibers with an aqueoussolution containinga detergent of the group consisting of a neutral soapand borax and a reversible poly- 25 merization product of formaldehydefree from extraneous substances at a temperature at which the meltingpoint of such constituent is lowered and aldehyde combines with themolecules of the fiber.

3. In the treatment of'keratinous fiber having a natural gummy or greasyconstituent, the steps which include impregnating the fibers in anaqueous formaldehyde neutral soap bo'rax solution de-. void of reagentscombining with formaldehyde in the presence of borax and at atemperature substantially in the range of to F. until the melting pointof such constituent islowered and an aldehyde radical has formed on thefiber, and substituting water for the aldehyde radical by oxidizing thealdehyde to acid in the presence of water prior to any reaction of theradical to form a condensation product.

wnmau BEACH PRATI'.

